1. Field of the Invention
The present invention relates to a message posting system in which each of users of a plurality of terminal devices connected to a server unit that provides a message board for each of a plurality of topics in which unspecified users can participate is allowed to post a message on a message board for an arbitrary topic.
2. Description of the Related Art
There are message boards which are provided on a network and on which unspecified users can post messages. Such message boards include a chat system which allows individual users to enjoy chatting in real time and a bulletin board on which individual users exchange opinions to develop a discussion. While those message boards differ from each other in whether or not the real-time action is involved, they basically do not have a significant difference in sequentially displaying messages posted by individual users. A topic is normally specified for a message board. Users post messages on a message board for the topic.
As unspecified users post messages on a message board, multiple users are likely to post messages in the same period. When many messages are posted in the same period, it is very difficult for each user to find a message on which the user wants to comment or find where the original message on which comments are given is located. A similar problem may occur for a message board which has a relatively low frequency of message posting if the viewing duration of a user becomes long.
Such a problem occurs prominently when a user is using a terminal device like a cellular phone whose display device is small in size or has a low resolution so that the number of displayable messages is small. Even when a user scrolls the screen to refer to old messages, it is very difficult to find a desired message in a huge number of messages. Even if the user finds the desired message, the operation for the searching is troublesome. It is possible that the contents of messages posted on a message board by some users are not related to the topic of the message board. It is difficult for new users to post messages on a message board containing many messages which are not related to the topic of the message board.
Japanese Patent Application Laid-Open No. 2007-42137 discloses an art of extracting remarks of designated users alone and displaying the remarks on a message board to overcome the foregoing problem of a message board which allows unspecified users to post messages. Japanese Patent Application Laid-Open No. 2006-227711 discloses an art of analyzing messages posted for each community (the same concept as a topic) and classifying discussions currently given in each community.
According to the art disclosed in Japanese Patent Application Laid-Open No. 2007-42137, each user can follow messages posted by other designated users. It is not however guaranteed that designated users are posting only messages related to a given topic (topic of the message board). According to the art disclosed in Japanese Patent Application Laid-Open No. 2006-227711, if messages posted on a community belong to the same classification, each user can easily grasp what kinds of messages are posted on the community at present. When messages belonging to different classifications are posted in parallel, however, the messages may not be classified properly. This art is very vulnerable to so-called troll.